Research On Moats In The Song Dynasty

The moat was the first main fortification for Chinese ancient cities.It was also an important component part of military water utilization.The theory of ancient moat construction and the theory of offensive/defensive equipments or other related theories roughly went through four stages: initiation and foundation during the Warring States period,development and maturity from the Tang Dynasty to the midterm of Northern Song Dynasty,inheritance and mutation from the later period of Northern Song Dynasty to the Southern Song Dynasty,maintenance and finalization from later period of the Ming Dynasty to the midterm of Qing Dynasty.Department of Civil Construction and Ministry of Building Works in the Song Dynasty were successively responsible for establishing the urban moat for various cities in the nation.East and West Renovation Department worked with Kaifeng Prefecture in dredging the rivers.The expenditure was allocated by the royal treasury.In local cities,county magistrates and leaders were directly in charge of establishing the moat.Royal court and local government allocated the expenses.In the Song Dynasty,builders and constructors for urban moat included soldiers of Xiang force,forced laborers of impressment and employed civilian workers.After the urban moat was completed,the central government took necessary measures to protect it.In the Song Dynasty,urban moats were divided into three types: artificial,semi-artificial and natural.As for advantages of the artificial moats,urban sites were selected at random.Military defense was deliberately designed with low risks of inundation.The disadvantages were concerned with massive engineering quantity and high costs due to complex construction.As for advantages of the semi-artificial moats,engineering quantity was less and water source was guaranteed.The disadvantages were related to limited choices of urban sites.Water source of urban moat was easily affected by the weather.Natural moats were the minority among all types of urban moats.Its advantages and disadvantages lie somewhere between the former two.With the constant expansion of urban scales and increasing military pressure,a part of the natural moats were promoted to semi-artificial moats,a part of semi-artificial moats were promoted to artificial moats.Artificial moats were built in different lengths,which were “constructed around cities and formed systems”.When it comes to the widths of artificial moats in the Song Dynasty,prefecture widths ranged from three to ten zhang.County widths ranged from one to three zhang.As for the Southern Song Dynasty,the width of artificial moats generally increased in prefectures.Most artificial moats,which were more than ten zhang,were constructed during the Southern Song Dynasty.Moreover,the actual depths of artificial moats conformed to construction theories in different cities.They were not more than two zhang deep in most cases.Lakes and rivers were the primary water source for artificial moats.Tides and underground water served as supplementary water sources.To ensure the stable water quantity for artificial moats,water conservancy facilities,such as water retaining dams and sluices,were built up on both sides.In the Song Dynasty,the frequency of artificial moat dredging in cities in terms of city level,from high to low is capital,military center,regional central city,and general state and county cities.In terms of spatial distribution,frontier defense area cities are higher than inland cities.Cities in the south are higher than those in the north,and cities in the Jianghuai region are higher than those in other regions.When it comes to the distribution of time,in spite of three peaks in dredging urban moats during the Northern Song Dynasty,the overall frequency was still lower than the Southern Song Dynasty.There are two reasons for significant changes in frequency and scales of artificial moats.Firstly,the layout of “city as the point and river as the line” developed in the national defense strategies.Secondly,improvement of entrenchment construction by Jin Mongol(Yuan)soldiers and constant innovation of artillery technology in defense battles.In Wartime,whether there is water source or not and meteorological factors,such like the temperature and rainfall are affect defense effect of moats actually.With the continuous development of city defense battles between Jin Mongol(Yuan)and Song Dynasty,urban moats became an increasingly essential part of city defense system.Besides,they were also the central targets for both sides in battles.